Environmental laboratories to analyze groundwater sources from public water supplies for Cryptosporidium and Giardia as part of efforts to identify sources under the direct influence of surface water (GWUDI), as required by federal regulations. MDH has previously identified GWUDI sources in 1994 and 1999 but continues to re-evaluate sources as new data and systems emerge. A 2014–2016 study revealed higher-than-expected occurrences of Cryptosporidium and Giardia, prompting MDH to revise its GWUDI identification methods. This aligns with a 2023 recommendation from the National Drinking Water Advisory Council to re-examine GWUDI definitions. MDH has developed a logistic regression model to predict high-risk sources and will collect well samples to validate the model’s effectiveness
